Geometry of cell division in Staphylococcus aureus.

The process of division in Staphylococcus aureus was examined by phase-contrast microscopy. The organisms appeared to divide in three alternating perpendicular planes, with sister cells remaining attached to each other after division. The resulting point of attachment was usually not exactly at the point corresponding to the center of the previous septal disk. Moreover, sister cells often changed position with respect to one another while still remaining attached. These factors are apparently responsible for the irregularity of staphylococcal clumps. Studies with penicillin and the examination of thin sections in the electron microscope confirm the conclusion, based upon light microscopy, that successive divisions in S. aureus occur in perpendicular planes.